In a typical wireless communications network, for example, a Long Term Evolution (LTE) network, selection of a shared data channel is based on a scheduling/grant mechanism, and is completely controlled by a base station (BS). In the mechanism, a network device sends, to a terminal device, a control channel used to schedule a data channel. Control channels may be classified into two categories. One is downlink grant (DL Grant). The network device sends a downlink grant to the terminal device to notify the terminal device of a downlink transmission resource allocated to the terminal device, and accordingly the terminal device receives downlink data on the granted downlink transmission resource. The other one is uplink grant (UL Grant). The network device sends an uplink grant to the terminal device to notify the terminal device of an uplink transmission resource allocated to the terminal device, and accordingly the terminal device sends uplink data on the granted uplink transmission resource.
When sending the control channel, the network device needs to map the control channel to a control channel element (CCE). However, the network device performs random mapping when mapping the control channel. Consequently, the terminal device has to perform blind detection a plurality of times to obtain the control channel, and complexity of blind detection on CCEs by the terminal device is high.